1Z0-006 Data Modeling 5

Question 1

In data modeling terminology, what is a 'candidate key'?

Accepted Answer

A minimal set of attributes that can uniquely identify every row in a table

Answer

A candidate key is any minimal set of attributes that uniquely identifies each row; one candidate key is chosen as the primary key, and the rest become alternate keys.

Question 2

What does 'participation constraint' (also called 'existence dependency') define in an ERD?

Accepted Answer

Whether every entity instance must participate in a relationship (total) or may optionally participate (partial)

Answer

Participation constraints specify whether all (total/mandatory) or only some (partial/optional) entity instances must be involved in a relationship.

Question 3

A PRODUCT table has columns: ProductID, CategoryID, CategoryName, Price. CategoryName depends on CategoryID, not directly on ProductID. Which normal form violation does this represent?

Accepted Answer

3NF violation due to a transitive dependency

Answer

CategoryName transitively depends on ProductID through CategoryID (ProductID → CategoryID → CategoryName), which violates 3NF.

Question 4

Which modeling concept does an ERD's 'IS-A' (generalization/specialization) hierarchy represent?

Accepted Answer

An inheritance relationship where subtypes share attributes of a supertype

Answer

An IS-A hierarchy represents generalization/specialization, where subtypes (e.g., HOURLY_EMPLOYEE) inherit common attributes from a supertype (e.g., EMPLOYEE) and add their own specific attributes.

Question 5

What is a 'natural key' in database design?

Accepted Answer

An identifier derived from existing real-world data attributes that naturally uniquely identifies a row

Answer

A natural key uses real-world data (such as a Social Security Number or ISBN) that inherently and uniquely identifies an entity.

(1Z0-006) Oracle Database Foundations Associate Practice Test

(1Z0-006) Oracle Database Foundations Associate Practice Test

1Z0-006 Data Modeling 5